Interlocking system for railroads



Feb. 7, 1933. w ow 1,897,005

INTERLOCKING SYSTEM FOR RAILROADS Filed Sept. 12, 1929 2 Sheets-Sheet 1BY zd7%%,

M MM

fly ATTORNEY Feb. 7, i933.

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W. K. HOWE INTERLOCKING SYSTEM FOR RAILROADS Filed Sept l2, l929ATTORNEY 2 Sheets-Sheet 2 Patented Feb. 7, 1933 UNITED STATES PATENToFFICE WINTHROP K. HOVE, OF ROCHESTER, YORK, ASSIGNOB TO GENERAL RAILWAYSIGNAL COMPANY, OF ROCHESTER, NEVJ YORK INTER-LOCKING SYSTEM FORRAILROADS Application filed September 12, 1929. Serial No. 392,138.,

his invention relates to power interlocking systems, and moreparticularly pertains to indication means and devices for such systems.

In power interlocking systems, it is desirable, for reasons familiar tothose skilled in the art, to provide indication latch mechanisms for thelevers controlling the operation of switches and signals, and to providesuitable means for releasin such an indication latch mechanism for aparticular lever when the switch or signal, controlled by that lever,has properly operated or responded. In one type of indication system, towhich the present invention more particularly relates, current from abattery or other suitable source located at the switch machine, iscontrolled by contacts operated by the switch machine and is transmittedto the tower to doe employed for actuating the indication latchmechanism.

In the type of indication system above described, some times called aconstant current or battery type of indication in contrastto "thedynamic type of indication, it may happen that an improper or falseindication can be given under a certain combination of circumstances.For example, when the operator moves his control lever to a newposition, 7 Of n I n there is a short interval of time, after powerisapplied to the switch machine, during which the contacts of the switchmachine controlling the indication relay remain closed and theindication relay is energized; and if 3a the operator should quicklyreturn the control lever to its former position, the indication latchmechanism may be released, even though the operation of the switchmachine from its former position has been initiated.

R n a Under such cond1t1ons, if provisions are made so that the switchmachine will EtlltOlllEltl-r cally reverse and follow the movement ofthe control lever to its original pos1t1on, no particular y unsafecondition results; but, if the "switch mach ne should fail to reversedue to failure of parts, blowing of the fuse by exces- .sive currentoccurring by such quick reversal of the control lever, or the like, theinertia of the motor armature and the gearing of the switch machinemight 'unlock the track switch proposed in accordance with the presentin-;

vention, to provide a time element device which is set into operationupon each movement of the control lever to a new operating position toprevent the actuation of the indi-' cation latch mechanism for a limitedtime after each such lever movement, sufiicient to assure such operationof the switch machine as will deenergize the indication relay and avoidan improper indication under such conditions above explained.

It is a further object to provide such a time element device coactingwith its asso ciated lever in a manner to leave the normal facility ofoperation unaffected. I

In describing the invention in detail, reference will be made to theaccompanying drawings, in which like reference characters refer to likeobjects, and in which Fig. 1 is a diagrammatic view of one specificembodiment of the present invention as applied. to one type of anelectrically operated switch machine having a constant current 7 type ofindication system.

Fig. 2 is one modification of the present invention;

Various other objects, purposes and characteristic features of thepresent invention will be in part obvious and in part pointed out as thedescription of the invention progresses.

A still further object isto provide an economical control of the switchposition repeating relay by the use of superimposed alternating currentover the control wires of the switch machine.

With reference to Fig. 1 of the drawings,

a track switch TS is shown as operatedby a suitable. switch machine SM,which is preferably of the type described in my Patent. No. 1,466,903,dated September 4,1923. This i switch machine SM has the usual armatureA and field winding F, and also associated therewith various groups ofcontacts.

ing contact between certain pairsof fixed,

contacts in either thenormal or reverse extreme pos1t1ons,be1ngoperatedto such positions mechanically by theswitch machine at thecompletion of the corresponding operation; and are operated to anopposite position in midst-roke of the switch-.machine'by the 5energization of a corresponding pair of two airs of poleichan'ging coils7 and-8. "The contacts includedj withina dotted rectangle designatePCCareknown as pole" changer coil contacts and includea movableolcontact'block 9 of insulating material which furnishes a mounting-forthe contacts '10 I and 11. -Tl'1e polechanger coil contacts PCG l"include two pairs-'oflfijxed contacts, one of when; the contact block'9is in eithera nor mal'or reverse position, and both" of said pairs beingelectrically interconnected when i 1 the contact block'9'is in anintermediate'posi-f tion., Thls movable contact block 9 is oper- 91ated' t'o'normal or reverse 1 extreme positions at the end ofeach'corresponding'operation of the switch machine fSM; and is caused toassume an intermediate position during the operation of 'the'switchmachine or any other timethat it isunlocked; a

The contacts includedfwithin adotted re'ctangle designated PD are knownas point detector contacts and include amovable con- 40V tact block12ofinsulating materialwhichis caused to'assume extreme normal and reversepositions when thetrack switchi'sf in corre sponding positions andlocked; but it is,

, caused to assume an intermediate position when the track switchisbeing operated from "'one extreme position towalnother', .or at a nysuch time that said track switcliis unlocked,

Mounted upon the movable contact block 12, there arecontacts 13 and;1,4-,;,which ,make

', contact; between their respective pairs j Of fixed QOntactSjWhen inthe normal or reverse. extreme positionsonly; a shunt contact 17. biasedtowarda contacting position, is actuated to anon-contacting position.only when.

the'movable contact block12 is in a normal position; a similarshuntcontact-11 8 biased v toward a contacting position is actuated'toanon-contacting position only} when the mov-- b able'contaet block 12an'extreine reverse position. example ofan operating mech anism of suchpoint detector contacts 11sdis?v closed in, 'the patent to Bushnell,N01."

1,517,236,, dated November" 25, 1924." v Asmara w h the; H st. et casaid pairs being electrically interconnected" tacts PD, there is a localtransformer T, the primary of'which is supplied with potential from asuitable alternating current source over va transmission line extendingfrom the interlocking tower.

In the tower, acontrol lever L is provided being capable of assuming theusual full normal and full reverse positions indicated by the arrows Nand B respectively as they ap- -.pear opposite an arrow A on thelev'erL.

These full positions of the lever L are supplemented by the normal andreverse indicating positionsfdesi'gnated by the arrows NI and RIrespectively-,which indicating positions aredetermined by an indicationlatch mechanism IM including an indication magnet 19 and-plunger 20.;The movementof the lever-L froma full position to an indica-L- tionposition operates a tappet bar 2lto a central positionby means of a camslot 22 in the usual well known'manner.

a The leverL also governs the operations the switch machine SM overnormal-and reverse operating wires N and B respectively in" con unct1onwith a common return wire C,.the operating and indicating circuits-being completed over these wiresby movable contact members 27, and29which make contact between certain pairs-of fixedcontacts -.whenthelever Lis in the positions N and NI, and make contact between certainother pairs of'fixed' contacts when the leverL is in the position R andRI;

A lever lock2 3 is provided to lock the lever- L against movement fromits full normal or full reverse position when the detector track isection associatedwith the track switch TS is shunted; The conditions ofthis detector track section is repeated by a track repeater relay TRwhich is controlled by a track relay T atlthe switch. 1

dissociated with the indication'latch mech' anism TM is anSS relayhaving a local phase winding 30 continuouslyenergized from a secondaryofalocal transformerT and havlng its linephase winding 32 energized overtwo line wires from the secondary of the local transformer T inaccordance with the position and locked condition of the track switchTS. This SS relayhas' a contact 33 which assumes eitherof'two extremeposi,-

tion'sldependingupon the relative instantafneous' polarity ofthecurrentsflowing in the 5 local phase winding BO anditheline phase winding 32,and"assumes a deenergiz'ed 'cen- 1 tral position when either'orbothphase wind-- 1 ings are deenergized. y

A'time element'device TE is operated by k the lever L each time the saidlever is moved tea new operating position. This time ele- Two energysaving contacts 24 and 25" are provided which may be actuated tocontacting'positionsby the control ofa 'lever latch ment device TE isdiagrammatically shown as a tooth plunger 42 slidably attached to theframe of the interlocking machine represented by portions 43 and 44 andis biased to a contacting position with the surface of le ver L by aspring 45. Attached to this plunger 42 and insulated therefrom is acontact member 46 which electrically interconnects two fixed contactsconventionally shown as arrows. A roller is mounted upon the lowerextremity of the plunger 42 to eliminate the contacting friction betweenthe plunger 42 and the surface of the lever L. On the surface of thelever L over which the roller 47 travels, a projecting cam 48 isprovided to force the plunger 42 in an upward direction when the leveris moved from a normal operating position to a reverse operatingposition. This motion is su'liicient to move the contact member to anon-contacting position which position is maintained for a predetermineddesired period of time by means of an escapement mechanism including agear 50 which engages with the teeth upon the plunger 42, a shaft 51connecting the gear 50 with a ratchet gear 52. An escapement wheel 53 issupported upon the same axle 51 in a. manner that the ratchet gear 52may rotate in a clockwise direction freely, but can not rotate in acounter clockwise direction due to the engagement of a spring biaseddetent 54 being biased by a spring 55. An escapement pawl 56 is providedto prevent the rotation of the escapement wheel 53 in either directionexcept at a predetermined rate.

Thus, when the cam upon the lever L is moved under the roller 47, themotion of the plunger quickly rotates the ratchet gear 52 a clock-wisedirection while the escapemcnt wheel does not appreciably rotate due tothe detaining effect of the escapement pawl 56. However, the sp ing 45tends to move the plunger 42 in a downward direction as soon as the cam48 moves from the roller 47. but it can only do at a rate determined bythe rate at which the escape me wl eel 53 rotate in a counterclockdirecton. as the gear 50, shaft 51 and are not allowed to rotatefree caused to rotate synchronously with escapemcntwheel due to theengagement of detent 54.

Thus, the contact member 46 is raised to a no- -contacting positionoachtime the lever of the operation of an interlocking system in which sucha time element device is included.

Operation of the system the normal function.

.Vith the apparatus and circuits of the interlocking system in thenormal condition as shown, tae contact 33 of the SS relay is in a hthand energized position as the local f) is continuously energized andthe ase winding 82 is energized over a al energizing circuit completedwith t 1e track switch TS and switch machme SM 111 1101 al lockedposltions.

i )rmal energizing circuit for the line phase winding 32 for the relaySS is traced as follows :from the right hand terminal of the secondaryof transformer T, through wires 60 and 61,-contacts 62 13. wires 63, 64and 65, winding 32 of relay SS, wires 66, 67 and 68, contacts 6914,wires 70 and 71, to the left hand terminal of the secondary oftransformer T. p

Let us assume that the operator desires to reverse the track switch TSand to do so presses the lover latch 26 preparatory to moving the leverL in a left hand direction. This opera ion closes the energizing thelock 23 and the indication magnet 19 respectively.

The energizing circuit for the indication magnet 19 is traced as follows:--from a suit- Assuming the detector track section govern ng the relayT tobe unoccupied, the ener- ,q'izing circuit for the lock 23 iscompleted through a circuit traced as follows :from the positiveterminal of a suitable source of potential indicated as 13+, throughfront contact 78, wire 79, closed contact 25, wire 80. winding of magnet23, to the opposite terminal of the suitable source indicated as l Withthe electric lock 23 energized, its plunger is moved to such a positionthat the lever L may be moved in a lefthand direction. hen the lever Lis moved beyond the normal indication position N1, the circuit for thein dication magnet 19 opened at contacts 76,

circuits through contacts 25 and 24 for energ1zmg,

permitting a forcedro p cam 81 to force the p1unger'20 downw'ard-into alocking position which prevents movement,,.of the lever L beyond thereverse indicating'position RI.

7 During the movementof the'lever L from the position NI to theposition'RI the plunger 42 is actuatedto an upper extreme'position bythe cam 48 which moves the contact mem-.' ber 46 .to a non-contactingposition, as heretofore described. I

. With the lever L in thereverse indicating position RI, the reverseoperating circuit for the switch machine SM is completed which causesthe switch machine to unlock and operate the track switch to a reverseposition and then again lock the switch. This operatingcircuit'fortheswitch machine SM is traced as follows from theipositive terminal ofa'suitable source of electrical potential indicated as 13+, through thefuse Y 49, wire 82,contacts 8327, wire 84, reverse.

operating wire R, wire 85, 7 contacts 866, 7 wires 87' and 88,'armatureA, wire 89, contacts 905, wires 91 and 92, "field winding F, wire 2593,'through the common wire CV to the oppo site terminal of the suitablesource of elec trical potential indicated as.B.'

As soon as the switch machine armature AQhaSj completed acertainnumberof revolutions to unlock the switch-machine SM and track switch TS, thecontact block12 assumes a central position, in which position thealternating current'suppliedto the line .phase windi ng 32 .overacircuit heretofore traced is opened at the vcontacts 6213 and 69--14';"also the control wires 65 and 66 are cshunted bythelshuiit'contacts 17 and 18 through wires-94, shunt contact17,-fiXed con- ;tactmemberj95, wire:96,';fshunt contact 18, fixed'coiitactf97, wires 98 and67. Thus, the

;cbntac t 33 ,of the SS relay is assured ofbeing operated toa centraldeenergized'position, I

Also, with the switch machine SM unlockedandiin operation, the contactblock 9 1s operated to a central position sothat' elther' the pole.changer coils 7 v ofthe pole changer coils 8may be energized accordingtowhether the reverse operating wire R orfthe normal eratingwire'N isenergized. with positive potentiaL' In other words, with the reverseoperating wire Rf energized the coils 7 are energized'to hold thecontact block 4 in its present position even though the switch ma- 5;chine SM is unlocked, through a circuit including wire 99, contacts10010, wire 101,

coils 7, wire 102, through the wire to'negative potential. Also, withthecontact block 9 in a central "position should positive po-. coitentialbeapplied tothe normal operating wire thev pole-changer coils-8 would beenergized through wire 103, contacts '10411.'

wire 105, 'pole changer coils 8,-wire 106,

" QlVith the contact block 4 in sition, thus resulting in" the reversalof thei switch machine armature A.

Withthe switch machine SM and track to disengagethe lever L, andallowingthe .op- .erator to control saidjlever. L to its full ree: ,verseposition- R.

, Assuming that'the switch machine SM and track switch TS have operatedto reverse positions and locked conditions, the contact blocks 4, 9 and12 are also operated toree verse extreme positions. t a reverse posi-;-tion, a snubbing circuit for theswitcliymachine SM is completed whichdynamically. brakes the momentum of. the armature A.

This dynamic snubbing circuit is traced as I follows from the upperterminal of armature A, through wires 89 and-113, contacts -1146, wires115, normal operating wire. N, wire 116, contacts 11728, wirell'8, com-1mon wireO, wire93, field winding F wires 1 92and '1l8, contacts1195,,wire 88, to thelower terminal of armature c j With the contactblock 12 in a reversepo-i sition, the shunt contact18 is actuated to anon-contacting position, so thatfwith -ithe' contacts 13 and14'in=reversepositions, a 7

reverse energizing circuitiforthe line phase winding 32 for the relay.SS is completed, which. is traced as follows from the;.right handterminalof thesecondary of transformer T, through wire 60, contacts 107:14,

wire 66, line phase winding 32,wires 65,164

and108,contacts 109 -13, wire 71,-to the left fin handterminal of the:secondary of transformer T.; I 'Inasmuch as I polarity- 0f theline phasewinding 32 has been reversed in respectto the instantaneous polarity inthe local phase winding 30, the c contact 33 assumes a left-hand dottedlineposition." The contact 33'and the contact member 7 29 are incorresponding positions,

so when the operator'again presses the lever latch 26 closing thecontact 24, the indication magnet 19 is energized inasmuch as the timeelement device TE is in a normal biased position. This energizingcircuit for the indication magnet 19 is traced as follows from thepositive terminal of suitable sourceof electrical. potential indicatedas B through closedcontact 24, wire 72, closed contact 46, wire 73,coils ofindication magnet 19, wires the instantaneous relative,

; through the wire C'to negative "potential, to

V 74 and 110, contacts 111-29, wire 112, con 65 control the contactblock 4 to areverse potaiiti'sgjiniai'lefi hand dotted line position,to

the opposite terminal of the suitable source indicated as B. The plunger20 is now operated to a disengaging position in respect to lever L, sothat the lever may be moved to its full reverse position B.

One operation of the specific interlocking system, including the timeelement device of the present invention, has been shown and described.It is obvious that the normal operation of the system is not in anymanner retarded or hindered from completing its normal operatingfunctions due to the in corporation of the time element device withinthe system. However, in order to make clear the usefulness of such atime element device, the case or combination of circumstances, in whichsuch a device is made necessary, will now be considered.

Referring to the operation ofthe lever L from the normal position N tothe reverse position R just described, let us assume that the lever Lhas been moved to the reverse indication position RI, and the operatorchanges his mind and tries to quickly change the lever L to its normalposition N. Such a movement of the lever L can not be accomplished asthe movement of the contact member 46 to a non-contacting positionprevents the energization of the indication magnet 19, thus preventingthe release of the indication latch mechanism IM which prevents themovement of the lever L from being moved to a full position.

Let us assume, that the time element contact 46 is not in place and thewires 7 2 and 7 3 are permanently connected together. Then the lever Lupon being quickly returned to its normal indicating position NI willhave given the armature A a chance to make several revolutions whilesaid lever L was still in the reverse indicating position RI. Then, withenergy now upon the normal control wire N, the pole changing coils 8 areenergized moving the contact block 4 to a reverse position, so that thearmature A will start revolving in an opposite direction if the fuse Fdoes not blow out. However, due to the lack of a counter electromotiveforce within the motor, a sudden inrush of current occurs and is likelyto blow the fuse F. Assuming that the fuse F does blow out and thearmature A continues rotation due to its inertia and the momentum of theswitch machine gearing, th n the contact 33 would still be in a normalenergized position as the switch machine is not unlocked when the leverL is reversed. Thus, the normal energizing circuit for the indicationmagnet 19 is completed, allowing the lever L to be returned to its fullnormal position N, but the momentum of the motor continues to operatethe switch machine SM to an unlocked condition. Should a train now passover the track switch TS the vibration might be sufficient to cause theswitch points to slightly open, so that a flange of-a car wheel mightbecome engaged with the open point and cause the train to split theswitch.

From the foregoing description, it is seen that the possibility of afalse or hang over indication of an interlocking system without the timeelement device of the present invention, is due to a time intervalduring which the indication relay contacts indicate the true position ofthe switch, and during which an cause further operation for one-halfunit of time after power is cut off. Then, if the operator returns thecontrol lever to a former position when three-fourths of this first unitof time has elapsed and the fuse blow out, the

control lever may be returned to the full po sition although the switchmachine. continues to move for one-half unit of time, thus unlocking thetrack switch. Obviously the SS relay cannot indicate the track switch asunlocked until the condition exists. I

Should a switch machine be so constructed as to be able to stopimmediately as soon as its power supply is removed, the condition mightarise in which the power cut-out might open the circuit ust as the trackswitch is unlocked with the control lever reaching its former positionat the same instant. Such a condition would still be undesirable.

However, the present invention provides a true compensation for suchconditions, in

that a time element is used to counter-act an undesirable time element.i

It is obvious from the above description, that the time element deviceof the present invention may be varied to operate through a period oftime 1n accordance w1th the conditions to be met in practice, whichperiod of time for the. specific case stated above is pref erablysllghtly greater than the time required for the switch machine to unlockthe trackswitch.

Other means have been proposed for use in battery type indicationsystems, such as a quick acting switch which selects the circuit for theopposite or next indication when the control lever is moved from theother or its last indicating position to its corresponding fullposition. Such a device prevents the returning of the control lever toits former position until after the originally intended'operation of thelever is completed. The interlocking system of the present inventiongives no such undesirable results.

With reference to Fig. 2 of the drawings, a modification of the SS relaycontrol is shown,

" i so which provides an economical means of ac- .Icomplishing suchcontrol. The. devices in Fig. 2 which are similar to devices in Fig. 1

-have been shown'nwith the same reference characters having distinctiveexponents, 1 In other Words, the devices in Fig, 2 wh ch have 1 the samereference characters with distinctive exponents, are the same devicesincluded in another circuit arrangement according to the invention andare operatively associated the supply of alternating current potentialto the primaryc Winding of a transformer T,

' with the secondary of this transformer connected in series with thecommon Wire C.

."ThUS, with the line phase winding 32? of the V irelayfSS connected inseries inthe wire 118' (see 1) which compl'e'tes the snubbing I flastsnubbing circuit of the switch a hi *motor," r

' Movable contacts 13 and inthe same manner-as explained for'Fig. 1

in: 407 i r i v "When the track switch TS and switch ma A; resistance120 provided in the primary circuit ofthe transformer T to limit theeffectin the primary'winding' of the surge ofi the dynamic currentflowing inthe secondary winding; i Acondenser 121*is shunted across thefield Winding F. J

1 4 are controlled to make contact'between certain pairs offixedcontacts in ,order to provide the reversal of instantaneous polarityupon the primary of thetransformerf T as is obvious fromthe drawings.Likewise, the pole changer contacts PC and the'polechanger coil contactsFCC are. controlled in a similar manner as heretofore explained.

chine SM are in their normal locked posi- .tions,contacts 13 and 1 F areinthe" position,

shown, thus energizing the transformer T :"With these conditionsobtaining, alternating current is superimposedvuponthe snubbing IIcircuit of the switch machine, energizing the -line phase winding 32 ofthe relay SS field Winding F 'and condenser 1 21 in'm-ultis ,Iple, wires151 and 152, 'c0ntacts'90 5, wire "153 armature A, wires 15 l'and'155',contacts "866, wire 156, reverse-operating wire R,

contacts 157*F- -28 ,-wires 15 8 and 159, winding 32 0f relay SS, wire160,common wire C to the h ndterminal of; the secondary'oftransformer-'1'.

During the operation of the switch machine SM, the contacts 18 and llassume a central nonrcontacting' position, thus deenergizing thetransformer'T -When the control lever L is moved to the reverse positionthe ener .g'izing circuit for the line phase winding 32* presentinvention ilowmg clann's.

rsozoozs a er contacts PC and the pole-changer coil contacts PCC 'toitheir reverse positions in correspondence with: the controller contactsofthe-co'ntrol lever At such time, a reverse energizing circuitfor thelinephase' wind; ing-32 is completed, which is traced as fol lows fromthe right hand terminal of the secondary of transformer T through commonWiI'e' C field windingF and condenser 119%5, wit-e154, armature A, wires153. and 162, contacts H P-'6, wire 163-, normal oper- 121ismultiple,wires '15land 161', contacts ating wireNt, wire 164, contacts117 -28,

Wire 159, winding 32 0f relay SS, wire 160',

- common wire C, to theleft hand terminal of the secondary ortransformer Tf. clrcuit, a circuit arrangement is provided. so I "thatthe SS'relay may be controlled over the A contact '33 is operated to itsnormal position; as shown, when the normal energizing 1 circuit for theline phase winding 32 is completed, 'andfis energized to a left handdotted line position, when the reverseenergizingcircuit is completedthus 'heretoforeex'plained.

controllingcircuits as It "'s to' beinot'ed thatthe condensers 121 mayheomitted in -suchcases where it is possible -t0-use a comparativelyhigh; secondary voltage'on the transformer T "Thus,aninterlocking'system of the 'constant current or battery typei'ndicati'onsystern has been shown and'described as, provid- M 'in'g adequateindication control underthe va- "1 riou's exigencies 'of operatingconditions.

Also, an economical means of accomplishing such control has beenincluded as onemodi- :fication ofthe interlocking systemiof the presinout invention.

a One specific construction of devices andarrangemen'tof circuits,designed for use; in rconnection with one particular type of inter-"locking system, has been shown; however, -it is to be understood that;the various devices and circuitarrangements selected are to{facilitatethe' disclosure" and nature of the invention rather thanitsspecific form,and it is tobe further understoo'dthat various modi-'fications and adaptations may'be made withoutdepartingfrom'the spiritorscope'of the Having described claim:,

sociated Withsaid control ilever', indication 'mean'srcapable of"actuating said indication as demanded by thefolmy invention, I now1.1'In-an interlocking system of thetype shown. and-described, a controllever opera- "tively governing the movement of a switch machin'e, an"indication latch mechanism assaid switch machine are in correspondence,

-;and, a time element device operably prevents ing actuation of saidindication latch mechanism by said indication means for a predeterminedtime after each governing operation of said control lever.

2. In an interlocking system of the type shown and described, a controllever operaively governing the movement of a switch machine, anindication latch mechanism associated with said control lever,indication means capable of actuating said indication latch mechanismwhen said control lever and said switch machine are in correspondence,and a time element device including, a normally closed contact operablyactuated to a non-contacting position during each governing operation ofsaid control lever, and means operably preventing the return of saidcontact to a normally closed position until a predetermined time afteractuation, with said time element device preventing said indicationmeans from actuating said indication latch mechanism for a certain timeafter each governing operation of said lever.

3. In an interlocking system of the type shown and described; a controllever operatively governing the movement of a switch machine; anindication latch mechanism associated with said control lever;indication means capable of actuating said indication latch mechanismwhen said control lever and said switch machine are in correspondence;and a time element device comprising, a contact normally biased to acontacting position, actuating means operably moving said contact to anon-contacting position upon each governing movement of said controllever,

and means actively preventing the return of said contact to a normallybiased posi tion until after a predetermined lapse of time; whereby saidindication latch mechanism is prevented from actuation for a predetermined time interval after each governing movement of control lever.

In an interlocking system of the type shown and described; a controllever operatively governing the movement of a switch machine; anindication latch mechanism as sociated with said control lever;indication means capable of actuating said indication latch mechanismwhen said control lever and said switch machine are in correspondence;and a time element device comprising, a contact normally biased to acontacting position, actuating means operably moving said contact to anon-contacting position upon each governing movement of said controllever;

and timing means including, an escapement wheel, a one way ratchetconnecting said actuating means and said escapement wheel, and anescapement pawl regulating the rate of rotation of said cscapementwheel, whereby said timing means actively prevents the return of saidcontact to its normally biased position until after a predeterminedtime.

5. In an interlocking system for railroads, a control lever operablycontrolling a distant actuation of said indication latch mechanism aftermovement of said control lever from one operating position to anotheroperating no ition until after the lapse of a predetermined timeinterval.

6. in an interloc ring system for railroads, 1

a lever controlling a distant switch machine and capable of assumingeither a normal position, normal indication position, a re- 3 :eindication position or a reverse position, and means preventingmanipulation of l lever no: either normal or reverse inn positions tonormal or reverse positions respectively exceptupon indication that saidswitch machine is in a correspond position with said lever, said meansinan indication magnet, a switch rerelay controlling said indication andtime measuring means preventindication magnet'trom being con-V.-rematurely. In an interlocking system for railroads; a levercontrolling a distant switch machine being capable of assuming either anorduos mal position, a normal indication position, a

reverse indication position or a reverse posi tion, and means forpreventing manipnlaticn of said lever from either a normal or reverseindicating position to normal or reverse ms respectively except uponindication position with said lever, said means inan indication magnet,a switch reig relay; and time measuring means for iensating for thedelay in response of itch repeating relay to the condition switch machine.

n interlocking system for railroads, controlling a distant switchmachine tively except upon indication that said machine is in acorresponding posiwith said lever, with said means including, a switchrepeating relay, a time element contact opened by movement of said leverit said switch machine is in a correspoi'ida from either the normal orreverse indication positioin to the oppositejindication position andclosed in a predetermined time thereafter, cont rollercontactslcontrolled by said lever, said indication magnet being controlled bysaidswitch repeating relay in 0on junction with said time elementcontact and said controller contacts; r v

9. In an interlocking system for railroads, a control lever capable ofassuming any one of two extreme or two intermediate positions andcontrolling a distant switch machine, andmeans for preventing saidcontrol lever from being moved from a particular intermediate positionto either extreme position except. when said-switch machine hascompleted its operation in correspondence with said particularintermediate position, said means vincluding, an indication magnet, aswitchposition repeatingrelay, contacts controlled by saidcontroljlever, and atime element contact opened by certain movements ofsaid control lever andclosing apredetermined time thereafter, wherebysaid indicationmagnet cannot be energized after movement of said controllever untilsufiicient time has elapsed to allow saidtswitchmachine' toassume a position control lever. 1 a

10. In an interlocking system for rail -roads, a controllever capable ofassuming any one of two extreme positions, or any one of twointermediate positions and controlling a" distant switch machine, anindication latch mechanism preventing movement of said control leverfrom a particular interme- I diate" position to either, extreme Lposition,

-electro-responsive means for operating said latch when said switchmachine and said *tant switch machine.

lever assume corresponding epositions, and means preventingactuation ofsaid indication latch mechanism by said electro-responsive'means aftermovement of said control :lever from one intermediate position-to an 7other intermediate position until after *the lapse of a certainpredetermined time interval, whereby said control lever cannot beoperated out of correspondencewith'said dis roads, a control levercapable of assuming anyone of two extreme positions, or anyone of twointermediate positlons for controlling it unless said-{controllever".and said distant a distant switchimachine,anindication latchmechanism for'preventing said control lever being moved from aparticular intermediate 7 position to a corresponding extreme positionswitch, machine are in correspondence, and means preventing actuation ofsaid indication latch mechanism after movement of said control leverfrom corresponding extreme or intermediate positions to opposite extremeor intermediate positions until'atter the lapse of a certainpredetermined time interval,

incorrespondence with said V mechanism preventing said control leverfrom being moved from a particular intermediate position to a particularcorrespondmgextreme posltion except after being energized,

with said indication latch mechanism normal- 1y being capable of beingenergized when said controlelever and said distant switch machine areincorrespondence, and means -;p'reventing energization or said indicationlatch mechanism aftermovement of said control lever from positions incorrespondence I a with said switch machine to positionsoutfofcorrespondence with said switch machmeuntill after a certampredetermined lillIlGlIltGT- val, with said means including atime'element 7 contact, means for' instantaneously opening said timeelement contact operable by move- 7 ment ot' said lever, and meansoperable for slowly closing said time element contact ineluding anescapementlpawl.

a 13. "In an interlocking system for railroadsfa control levercapable'ofassuming any one of twoeXti-eme positions or-any' one of two-intermediatelpositions and controlling a dist'ant switch machine, anindication latch mechanism preventing said control lever from beingmovedfrom a particular intermediate position to a corresponding extremeposition except after being energized, with said'mechanism normallybeing capable of being ener- "gifted when said control lever and saiddis-" tantfswitch machine are in correspondence, and means prevent ngenergizatlon of sand. indicat on latch mechanism afterjmov-emento'f'saidjcontrol lever from one intermediate positlon to anotherintermediate positlon until after a certainpredetermmed time lnter-.val,"with said means including, a timelelement contact, means forinstantaneously openmg said time element contact including,are'

ciprocating' plunger, anda one-way ratchet, 3115 and means allowing saidtime elementcontact to close after a predetermmed time including anescap'ement pawl.;. v

14. Inan "interlocking system, a track switch operated by a switchmachine, a control' lever governing the operations. of said '1 switchmachine, anlindication latch mechanism preventing extreme movementslofsaid 7 control. lever except whentactuated, indication means including.point detector contacts operated by said track switchand saidswitchfn'iachine, an electro-responsive device indicatmg'the position of saidtrack switch, two *l ue' wires over wlnch's'aid electro-respons1vedevice is; controlled in Jaccordance with said ocking system forrailroads; 70

point detector contacts, with said'indication means capable of actuatingsaid indication latch mechanism when said track switch and said switchmachine are in correspondence with said control lever and locked, and atime element mechanism operably preventing said indication means fromactuating said indication latch mechanism during operation of saidswitch machine before said track switch is unlocked.

15. In an interlocking system, a track switch operated by a switchmachine, a control lever governing the operations of said switchmachine, an indication latch mechanism preventing extreme movements ofsaid control lever ev'cept when actuated, indication means including,point detector contacts operated by said track switch and said switchmachine, an electro-responsive device indicating the position of saidtrack switch, means operably controlling said electro-responsive deviceover the control wires of said switch machine in accordance with saidpoint detector contacts, with said indication means capable of actuatingsaid indication latch mechanism when said track switch and said switchmachine are in correspondence with said control lever and locked, and atime element mechanism operably preventing said indication means fromactuating said indication latch mechanism during operation of saidswitch machine before said track switch is unlocked.

16. In an interlocking system for railroads, track swi ch, a s vitchmachine for operatsaid track switch, a control lever, two control wiresand a common return wire between said switch machine and said controllever providing normal and reverse operating circuits for said switchmachine, and means for indicating the condition of said switch machineoperable by alternating current flowing in reverse and normal indicatingcircuits respectively including said operating circuits of said switchmachine.

17. In an interlocking system for railroads, a track switch, a switchmachine for operating said track switch, a control lever, two controlwires and a common return wire between said switch machine and saidcontrol lever providing normal and reverse operating circuits for saidswitch machine, an elec tro-responsive device in the tower indicatingthe position of said track switch and having normal and reverseenergizing circuits including said operating circuits of said switchmachine, means for energizing said electroresponsive device including, asecondary winding of a transformer in series with said common wire, acondenser for decreasing the reactance of said energizing circuits, andmeans for controlling the energization of the primary winding of saidtransformer in accordance with the condition of said track switch.

18. In an interlocking system for. railroads, a track switch, a switchmachine for operating said track switch, a control lever, two controlwires and a common return wire between said switch machine and saidcontrol lever providing normal and reverse operating circuits for saidswitch machine, a secondary winding of a transformer included in serieswith said common wire, contact means controlling the energization of theprimary winding of said transformer in accordance with the conditions ofsaid track switch and said switch machine. and a three position relay inthe tower operably controlled by the energization of said secondarywinding of said transformer over normal and reverse energizing circuitsincluding said normal and reverse operating circuits of said switchmachine, whereby the condition of said track switch is inoicated in thetower.

19. In an interlocking system for railroads, a control lever capable ofassuming any one of two extreme positions or any one of two intermediatepositions and controlling a distant switch machine, an indication latchmechanism when deenergized preventing said control lever from beingmoved from a particular intermediate position to a particularcorresponding extreme position, said indication latch mechanism normallybeing capable of being energized when said control lever and saiddistant switch machine are in correspondence, and means preventingenergization of said indication latch mechanism after movement of saidcontrol lever from positions in correspondence with said switch machineto positions out of correspondence with said switch machine until afterthe lapse of a certain predetermined time interval, said means includinga time element contact, means for instantaneously opening said timeelement contact operable by movement of said lever, and means operablefor slowly closing said time element contact including an escapementpawl.

20. In an interlocking system for railroads, a control lever capable ofassuming any one of two extreme positions or any one of two intermediatepositions and controlling a distant switch machine, an indication latchmechanism for, when energized, preventing said control lever from beingmoved from a particular intermediate position to a corresponding extremeposition, said mechanism normally being capable of being energized whensaid control lever and said distant switch machine are incorrespondence, and means for preventing energization of said indicationlatch mechanism after movement of said control lever from oneintermediate position to another intermediate position until after thelapse of a certain predetermined time interval, said means includlng, atime element contact, means for tablished so long as said leverand'switch instantaneously opening said time element contact including, areciprocating plunger, and a one-way ratchet, and means allowing saidtime element contact to close after a predetermined time including anescapement pawl.

21. In an interlocking system for railroads, the combination with adistant switch machine including an electric motor and a local lever,two control wires each used separately ina circuit with a common returnwire for operating said switch machine in opposite directions eachcircuit of which is established solong as said lever and switch machineare out of correspondence, an indicating relay associated with saidlever,itwo indicating circuits each including a different control wireand said common wire and completed only when said lever and sw tchmachine assume corresponding positions, said indicating circuitsincluding means for loy passing said motor to the flow of indicatingcurrent distinctive'in character from the current used for operatingsaid motor, v I i a 22. In an interlocking system for railroads, thecombination'with a distant switch machine including an electric motorand a local lever, two control wires each used separately in a circuitwith a common return wire for operating said switch machine inoppositedirections each circuit of which is es machine are out ofcorrespondence, an indicating relay associated with said lever andresponsive only to current distinctive from the current used foroperating said motor, two indicating circuits each including a differentcontrol wire and said commonwire and completed only when said lever andswitch machine assume corresponding positions, said indicating circuitsincluding me ans for by-passing said motor to the flow of saiddistinctive indicating current, and means for impressing on saidindicating circuits said distinctive, currents of distinctiveinstantaneous polarity corresponding .to the position of the switchmachine. s

23. In an interlocking system for railroads, a trackswitch, a switchmachine for operating said track switch, a control lever operable tonormal and reverse governing positions for governing said switch machineto-normalcr reverse positions respectively,'

indicationmeansfor indicating the position of SaId'tIaCk switch,electrores'ponsive means governed by said indicationmeans, and time ofsaid track's'witch, electroresponsive means governed sa d indicationmeans, time measuring meansinitiated by each operation of saidcontrollever for-preventing during a predetermined time thereafter thegoverningof said electroresponsive means by said indication means, saidtime measuring means including, a time element contact, means forinstantaneouslyopening said time element contact including,a"reciprocating plunger, and a one-way ratchet, and means allowing saidtimeelement contact to close after-a predetermined time said meansincluding-an escapement pawl 7 v 25. Inan interlocking system forrailro'a'ds, a track'switch, a switch machine for operating said trackswitch, a controllever operableto normal and reverse'positionsforgoverning said switch machine, a three-position relay for ind cating theposition and locked condition ofsaid track switch, electroresponsivemeans having the energization of its windings governed by saidthree-position relay, and time measuring means initiated by movement ofsaid control lever for preventing for a predetermined time thereafterthe energization of said electroresponsive means by saidthree-positionrelay. 26.. In an interlocking system for railroads; a. switch machine;a lever for controlling s aid switch'machinmfsaid lever being capable ofassuming either anormal extreme poistion, a normalindication position, areverse indication position or a reverse extreme position, with saidpositions being progressively attained; and means allowingmanipulation'of said lever from normal or reverse indication positionsto corresponding normal or reverse extreme positions only whensaid leverhasbeen in a particular indication position for a predetermined periodof time and measuring means initiated by each operationof said controllever forpreventing during a predetermined time thereafter thegoverningxof said electroresponsive means by said indication means.

24. In an interlocking system "for rail roads, a track switch, a switchmachine for operating said track sWitch,a control lever operable tonormal and reverse governingv

